Method of forming a capacitor with two diffusion barrier layers formed in the same step

ABSTRACT

The invention includes: forming a capacitor electrode over one region of a substrate; forming a capacitor dielectric layer proximate the electrode; forming a conductive diffusion barrier layer, the conductive diffusion barrier layer being between the electrode and the capacitor dielectric layer; forming a conductive plug over another region of the substrate, the conductive plug comprising a same material as the conductive diffusion barrier layer; and at least a portion of the conductive plug being formed simultaneously with the conductive diffusion barrier layer.

RELATED PATENT DATA

This patent resulted from a continuation of U.S. patent application Ser.No. 10/017,557, filed on Dec. 14, 2001, now U.S. Pat. No. 6,645,845which in turn is a continuation of U.S. patent application Ser. No.09/378,433, filed on Aug. 20, 1999 and now U.S. Pat. No. 6,333,225.

TECHNICAL FIELD

This invention pertains to semiconductive processing methods of formingintegrated circuitry, as well as to semiconductive device circuitry.

BACKGROUND OF THE INVENTION

A common method of forming memory devices is to form an array of devices(a so-called memory array), and to form control devices at a peripheryof the array. The memory array can comprise, for example, a dynamicrandom access memory (DRAM) array comprising arrays of capacitors andtransistors. The peripheral circuitry can comprise, for example,transistors. Frequently, the memory array circuitry and the peripheralcircuitry will be covered by insulative materials. Conductive contactplugs can be formed to extend through the insulative materials toelectrically connect peripheral circuitry and memory array circuitry toone another, or to other circuitry.

A continuing goal in semiconductor device fabrication is to minimizeprocess steps. Accordingly, it would be desired to develop processingmethods which reduce processing steps associated with forming memoryarray circuitry and peripheral circuitry.

SUMMARY OF THE INVENTION

In one aspect, the invention encompasses a method of forming circuitry.A capacitor electrode is formed over one region of a substrate and aconductive diffusion barrier layer is formed proximate the electrode. Adielectric layer is formed. The diffusion barrier layer is between theelectrode and the dielectric layer. A conductive plug is formed overanother region of the substrate. The conductive plug comprises a samematerial as the conductive diffusion barrier layer and at least aportion of the conductive plug is formed simultaneously with theconductive diffusion barrier layer.

In another aspect, the invention encompasses an integrated circuitcomprising a capacitor and a conductive plug wherein the conductive plugand capacitor include a common and continuous layer.

In yet another aspect, the invention encompasses a circuit construction.The circuit construction includes a substrate having a memory arrayregion and a region that is peripheral to the memory array region. Thecircuit construction also includes a capacitor construction over thememory array region of the substrate. The capacitor constructioncomprises a storage node, a dielectric layer and a cell plate layer. Thedielectric layer is between the storage node and the cell plate layer.The circuit construction further includes an electrical interconnectover the peripheral region. The interconnect is electrically connectedto the cell plate layer and extends between the cell plate layer and thesubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a fragmentary, diagrammatic, cross-sectional view of asemiconductive wafer fragment at a preliminary processing step of amethod of the present invention.

FIG. 2 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 1.

FIG. 3 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 2.

FIG. 4 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 3.

FIG. 5 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 4.

FIG. 6 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 5.

FIG. 7 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 6.

FIG. 8 is a view of the FIG. 1 wafer fragment shown at a processing stepsubsequent to that of FIG. 7.

FIG. 9 is a view of the FIG. 1 wafer fragment shown at a step subsequentto that of FIG. 6 in accordance with a second embodiment method of thepresent invention.

FIG. 10 is a view of the FIG. 9 wafer fragment shown at a stepsubsequent to that of FIG. 9.

FIG. 11 is a view of the FIG. 1 wafer fragment shown at a stepsubsequent to that of FIG. 3 in accordance with a third embodimentmethod of the present invention.

FIG. 12 is a view of the FIG. 11 wafer fragment shown at a processingstep subsequent to that of FIG. 11.

FIG. 13 is a view of the FIG. 1 wafer fragment shown at a processingstep subsequent to that of FIG. 6 in accordance with a fourth embodimentmethod of the present invention.

FIG. 14 is a view of a semiconductive wafer fragment shown at aprocessing step subsequent to that of FIG. 2 in accordance with a fifthembodiment method of the present invention.

FIG. 15 is a view of the FIG. 14 wafer fragment shown at a processingstep subsequent to that of FIG. 14.

FIG. 16 is a view of the FIG. 14 wafer fragment shown at a processingstep subsequent to that of FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

In one aspect, the present invention encompasses a recognition thatprocessing steps associated with the formation of circuitry over amemory array region of a semiconductive wafer substrate can beconsolidated with processing steps associated with formation ofcircuitry over a peripheral region of the substrate. Such will becomemore apparent with reference to FIGS. 1-6, which illustrate initialprocessing of a method of the present invention.

Referring initially to FIG. 1, a semiconductor wafer fragment 10comprises a semiconductive substrate 12. Substrate 12 can comprise, forexample, a monocrystalline silicon wafer lightly doped (i.e., doped to aconcentration of less than or equal to about 10¹⁶ atoms/cm³) with ap-type dopant. To aid in interpretation of the claims that follow, theterm “semiconductive substrate” is defined to mean any constructioncomprising semiconductive material, including, but not limited to, bulksemiconductive materials such as a semiconductive wafer (either alone orin assemblies comprising other materials thereon), and semiconductivematerial layers (either alone or in assemblies comprising othermaterials). The term “substrate” refers to any supporting structure,including, but not limited to, the semiconductive substrates describedabove. Semiconductive substrate 12 comprises a memory array region 14and a peripheral region 16.

Word lines 18, 20 and 22 are formed over substrate 12. Word lines 18, 20and 22 comprise a gate stack 24 and sidewall spacers 26. Gate stack 24can comprise, for example, layers of silicon dioxide, polysilicon andsilicide. Sidewall spacers 26 can comprise, for example, silicon nitrideor silicon oxide.

Field oxide regions 28 are formed over substrate 12 within memory arrayregion 14. Field oxide regions 28 can comprise, for example, silicondioxide.

Electrical nodes 30 and 32 are defined adjacent word line 18, andelectrical nodes 34, 36 and 38 are defined adjacent word lines 20 and22. Wordlines 18, 20 and 22 can comprise transistors, and nodes 30, 32,34, 36 and 38 can comprise source/drain regions of such transistors.Nodes 30 and 32 are proximate peripheral region 16 of substrate 12. Theterm “proximate” indicates that nodes 30 and 32 can be within, above orbelow peripheral region 16 of substrate 12 (embodiments in which nodesare elevationally displaced from substrate 12 are not shown). Similarly,nodes 34, 36 and 38 are proximate memory array region 14 of substrate12. Nodes 30, 32, 34, 36 and 38 can comprise, for example, conductivediffusion regions formed within substrate 12. Such diffusion regions canbe formed by, for example, implanting conductivity-enhancing dopant intosubstrate 12.

An electrically insulative layer 40 is formed over substrate 12, andover word lines 18, 20 and 22. Insulative layer 40 can comprise, forexample, borophosphosilicate glass (BPSG), and can be formed by, forexample, chemical vapor deposition.

Referring to FIG. 2, openings 42 and 44 are etched through insulativelayer 40 to nodes 34 and 38, respectively. Openings 42 and 44 can beformed by, for example, providing a photoresist mask (not shown) overlayer 40, and patterning the mask to expose regions of insulative layer40 at opening locations 42 and 44. Insulative layer 40 can then beetched with, for example, a fluorine-containing plasma to form openings42 and 44. The photoresist mask can be subsequently removed to leave thestructure shown in FIG. 2.

Referring to FIG. 3, capacitor storage nodes 46 and 48 are formed withinopenings 42 and 44 (FIG. 2), respectively. Capacitor storage nodes 46and 48 can comprise, for example, polysilicon and preferably comprisethe shown roughened outer surfaces 50 and 52. Such roughened outersurfaces can be formed by, for example, deposition of hemisphericalgrain polysilicon.

A dielectric layer 54 is formed over storage nodes 46 and 48. Dielectriclayer 54 can comprise, for example, one or more of silicon dioxide orsilicon nitride, and preferably comprises tantalum oxide. Dielectriclayer 54 can be formed by, for example, chemical vapor deposition.Storage nodes 46 and 48, and dielectric layer 54, can be formed bymethods known to persons of ordinary skill in the art, such as, forexample, chemical vapor deposition. In the shown embodiment, thematerial of storage nodes 46 and dielectric layer 54 does not extendover peripheral region 16. Such can be accomplished by, for example,masking peripheral region 16 while forming nodes 46 and 48, and whileforming dielectric layer 54.

Referring to FIG. 4, a photoresist masking layer 56 is provided overregions 14 and 16 of substrate 12 and patterned to define openings 58and 60 in peripheral region 16.

Referring to FIG. 5, openings 58 and 60 are extended to node locations30 and 32, respectively. Openings 58 and 60 can be extended by, forexample, a plasma etch utilizing a fluorine-containing component.

Referring to FIG. 6, photoresist material 56 (FIG. 5) is removed.Subsequently, a conductive material 62 is formed over both peripheralregion 16 and memory array region 14 of substrate 12. In the shownembodiment, conductive material 62 comprises two separate layers (64 and66). Layer 64 can comprise, for example, a metal nitride, such astitanium nitride or tungsten nitride, and layer 66 could comprise ametal such as tungsten, aluminum or copper. The metal of layer 66 can bein either an elemental form, or in the form of an alloy, such asaluminum/copper. Layers 64 and 66 can be formed by, for example,chemical vapor deposition and/or sputter deposition.

Layers 64 and 66 would typically have different functional purposes atperipheral region 16 relative to memory array region 14. Specifically,layers 64 and 66 form contact plugs 65 and 67 at peripheral region 16,with layer 64 preferably comprising a metal nitride and functioning asan adhesive layer for adhering metal layer 66 within openings 58 and 60(FIG. 5). Layer 64 can also function to prevent diffusion of dopant fromdiffusion regions 30 and 32 into metal layer 66. In contrast, layers 64and 66 form at least a portion of a capacitor electrode 81 over memoryarray region 14. Specifically, layers 64 and 66 together define at leasta portion of capacitor cell plate 81, with conductive material 62 anddielectric layer 54 being operatively adjacent storage node layers 46and 48 to form capacitor structures 70 and 72. In embodiments in whichdielectric layer 54 comprises tantalum oxide, layer 64 preferablycomprises a metal nitride. Layer 64 can then function as a capacitordiffusion barrier layer to inhibit undesired diffusion of materialsbetween tantalum oxide layer 54 and upper capacitor electrode layer 66.

Although material 62 is shown as comprising two layers, it is to beunderstood that the invention also encompasses embodiments in whichmaterial 62 comprises only one layer, and other embodiments in whichmaterial 62 comprises more than two layers. For instance, material 62can comprise three layers wherein a first layer is titanium deposited toform titanium silicide at the bottoms of openings 58 and 60 (FIG. 5),and the remaining two layers are a metal nitride layer (such as TiN) anda metal layer (such as Al).

In the shown embodiment, conductive material layer 62 is formed overperipheral region 16 and memory array region 14 in a common depositionstep. Thus, such embodiment consolidates formation of conductive contactplugs 65 and 67 with formation of capacitor electrode 81 over memoryarray region 14. Such can save process steps relative to prior artmethods which form conductive contacts over a peripheral region of asubstrate separately from formation of a capacitor electrode over amemory array region of the substrate.

FIGS. 7-10 illustrate alternative processing methods which can beutilized for patterning conductive material at peripheral region 16.FIGS. 7-8 illustrate a first embodiment method, and FIGS. 9-10illustrate a second embodiment method. Referring first to the embodimentof FIGS. 7 and 8, and specifically referring first to FIG. 7, aphotoresist masking layer 76 is provided over memory array region 14while leaving peripheral region 16 exposed to an etching process. Theetch process removes conductive material 62 from over insulativematerial 40 at peripheral region 16 to electrically isolate conductiveplugs 65 and 67 from one another.

Referring to FIG. 8, a conductive layer 80 is formed over memory arrayregion 14 and peripheral region 16 and patterned to form isolatedelectrical contacts with conductive plugs 65 and 67, and to form anotherportion of capacitor electrode 81 for capacitor constructions 70 and 72.More specifically, layer 80 and conductive material 62 together formcapacitor electrode 81 for capacitors 70 and 72. Conductive layer 80 cancomprise, for example, a metal such as tungsten, titanium, copper and/oraluminum, and can be formed by, for example, sputter deposition.Alternatively, conductive layer 80 can comprise a conductively dopedsemiconductive material, such as, for example, conductively dopedpolysilicon. Subsequent processing (not shown) such as provision of aninterlevel dielectric or spin-on-glass over one or both of regions 14and 16, followed by chemical-mechanical planarization can be conductedto form an insulative layer over regions 14 and 16.

Referring to the embodiment of FIGS. 9 and 10, identical numbering tothat utilized in describing the embodiment of FIGS. 7 and 8 will beused. A difference between the embodiment of FIGS. 9 and 10 and that ofFIGS. 7 and 8 is that in the FIGS. 9 and 10 embodiment conductivematerial 80 is formed over memory array region 14 and peripheral region16 prior to etching of conductive material 62.

Referring initially to FIG. 9, conductive layer 80 has been formed overmemory array region 14 and peripheral region 16.

Referring to FIG. 10, conductive layer 80 and conductive material 62 arepatterned in a common etch to electrically isolate conductive plugs 65and 67 from one another, and to electrically isolate the circuitry ofperipheral region 16 from that of memory array region 14. The patterningof material 62 and layer 80 can comprise, for example, formation of apatterned photoresis: layer (not shown) over layer 80, and subsequenttransferring of a pattern from the photoresist layer to underlying layer80 and conductive material 62 to form the structure shown in FIG. 10.The patterned photoresist layer forms a protective layer over a portionof conductive material 80 that is over storage nodes 46 and 48 thatprotects such portion of conductive material 80 as another portion ofconductive material 80 is removed from over peripheral region 16. Theportion of conductive material 80 removed from peripheral region 16 isproximate to where openings 58 and 60 (FIG. 5) were formed.

Another embodiment of the invention is described with reference to FIGS.11 and 12. In describing to FIGS. 11 and 12, identical numbering to thatutilized above in describing FIGS. 1-10 will be used, with differencesindicated by different numerals.

Referring first to FIG. 11, semiconductive wafer fragment 10 is shown ata processing step subsequent to that of FIG. 3, with a layer 90 formedover dielectric layer 54 in memory array region 14, and extending toover peripheral region 16. Layer 90 can comprise, for example, adiffusion barrier layer such as, for example, titanium nitride ortungsten nitride.

Referring to FIG. 12, openings are formed through layer 90 and to nodelocations 30 and 32, and subsequently filled with conductive material62. The formation of the openings and subsequent filling of suchopenings with conductive material 62 can occur through processingsimilar to that described with reference to FIGS. 4-6. Wafer fragment 10of FIG. 12 can then be subjected to subsequent processing analogous tothat of either the embodiment of FIGS. 7-8 or the embodiment of FIGS.9-10 to form isolated conductive plugs in electrical contact with nodelocations 30 and 32, and to form capacitor structures similar to thestructures 70 and 72 of FIGS. 8 and 10.

Yet another embodiment of the present invention is described withreference to FIG. 13 which illustrates a semiconductive wafer fragment10 at a processing step subsequent to that of FIG. 9. In the FIG. 13embodiment, conductive layer 80 and conductive material 62 are patternedto electrically isolate contact plugs 65 and 67 from one another, butcontact plug 67 remains in electrical connection with the uppercapacitor electrode 81 over memory array region 14. Thus layers 64 and66 are common and continuous layers comprised by both contact plug 67and capacitors 70 and 72. In the FIG. 13 embodiment, contact plug 67forms an electrical connection between memory array region 14 andelectrical node 32.

The embodiment of FIG. 13 can be advantageous over prior art methods forproviding a good electrical contact to a cell plate electrode.Specifically, prior art methods utilize electrical connects extendingupwardly from a cell plate layer. Such electrical connects are formed byproviding an insulative layer over the cell plate layer and etchingdownwardly through the insulative layer to expose the cell plate layer.Occasionally, the etch extends through the cell plate layer and resultsin a poor electrical connection to the cell plate layer. In contrast,the embodiment of FIG. 13 utilizes an electrical connection extendingdownwardly from a cell plate layer and formed during formation of thecell plate layer. Specifically, at least a portion of the cell platelayer 81 is preferably formed over electrical interconnect 67 duringformation of electrical interconnect 67.

It is noted that the invention also encompasses embodiments wherein cellplate layer 81 from memory array region 14 extends to physically contactmore than one contact plug in peripheral region 16. Such embodiments canprovide redundancy in the event that one or more of the connectionsfails. In the shown embodiment, interconnects 65 and 67 are connectedthrough a switch comprising word line 18. Interconnect 65 can then beconnected to other circuitry (not shown) to provide a switchableconnection between such other circuitry and the capacitor plate 81 overmemory region 14.

Yet another embodiment of the present invention is described withreference to FIGS. 14-16. In describing the embodiment of FIGS. 14-16,identical numbering to that utilized above in describing the embodimentsof FIGS. 1-13 will be used, with differences indicated by differentnumerals.

Referring to FIG. 14, wafer fragment 10 is illustrated at a processingstep subsequent to that of FIG. 2. Specifically, storage nodes 46 and 48are formed within openings 42 and 44 (FIG. 2). Wafer fragment 10 of FIG.14 differs from the wafer fragment 10 of FIG. 3 (which is also atprocessing step subsequent to that of FIG. 2) in that there is nodielectric layer 54 provided over storage nodes 46 and 48 in theembodiment of FIG. 14.

FIG. 15 illustrates the wafer fragment 10 of FIG. 14 after it has beensubjected to processing analogous to that described above with referenceto FIGS. 4-6. Specifically, a conductive material 62 has been formedover storage nodes 46 and 48. Conductive material 62 has also beenformed in electrical contact with node locations 32 to form electricalinterconnects 65 and 67 over peripheral region 16 of substrate 12. Asthere was no dielectric layer formed prior to provision of conductivematerial 62, material 62 electrically interconnects with nodes 46 and 48to effectively become a portion of the capacitor storage nodes 46 and48.

A patterned photoresist layer 100 is provided over peripheral region 16and memory array region 14. Patterned photoresist layer 100 has openings102 extending through it.

Referring to FIG. 16, openings 102 (FIG. 15) are extended toelectrically isolate electrical interconnects 65 and 67 from one anotherand from memory array region 14, as well as to electrically isolatestorage nodes 46 and 48 from one another. Photoresist layer 100 (FIG.15) is then removed, and a dielectric layer 54 is formed over memoryarray region 14. Dielectric layer 54 can be formed by, for example,processing described above with reference to FIG. 3. After formation ofdielectric layer 54, a conductive layer 80 is provide over storage nodes46 and 48, as well as over electrical interconnects 65 and 67.Conductive material 80 is then patterned to form a cell plate 81 overstorage nodes 46 and 48, and to form electrically isolated contacts tointerconnects 65 and 67. The formation and patterning of layer 80 can beconducted in accordance with the methods described above in reference toFIGS. 7 and 8.

The embodiment of FIGS. 14-16 forms a diffusion barrier layer 64 that ispart of capacitor storage nodes 46 and 48. In the shown embodiment,material 62 can comprise diffusion barrier components throughout itsthickness. Specifically, layers 64 and 66 can both comprise eithertitanium nitride or tungsten nitride.

It is noted that the embodiments described above form a diffusionbarrier layer as either part of a storage node, or as a part of acapacitor plate. The invention encompasses other embodiments (not shown)wherein one or more of the above-described embodiments are combined toform a diffusion barrier region as part of a storage node and to alsoform a diffusion barrier region as part of a capacitor plate.

It is also noted that there will typically be a bit line contact (notshown) formed in electrical connection with node 36 in the embodimentsdescribed above to connect node 36 to a bit line (not shown). Such bitline can be either above the capacitors (a so-called capacitor over bitline construction) or beneath at least a portion of the capacitors (aso-called capacitor over bit line construction).

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A method of forming circuitry comprising thefollowing steps: providing a substrate, the substrate including asemiconductor material; defining a memory array region of the substrateand an other region of the substrate soaced from the memory arrayregion; said other region comprising a conductively-doped region of thesemiconductor material; forming a capacitor construction over the memoryarray region of the substrate, the capacitor construction comprising apair of capacitor electrodes spaced from one another by at least adielectric layer and a first barrier layer; forming an electricalinterconnect over said other region of the substrate and in electricalconnection with the conductively-doped region the electricalinterconnect comprising a second barrier layer the conductively-dopedregion and a metal layer over the second barrier layer; and wherein thefirst and second barrier layers are formed in a same step.
 2. The methodof claim 1 wherein the first and second barrier layers comprise TiN. 3.The method of claim 1 wherein the first and second barrier layerscomprise TiN, and wherein the same step comprises chemical vapordeposition.
 4. The method of claim 1 wherein the first and secondbarrier layers comprise TiN, and wherein the metal layer comprises oneor more of Ti, W, Al and Cu.
 5. The method of claim 1 where the firstand second barrier layers are together part of a common and continuouslayer.
 6. A method of forming circuitry, comprising: providing asubstrate which comprises a semiconductive material; defining a memoryarray region of the substrate and an other region of the substratespaced from the memory array region; providing a first electrical nodeassociated with the memory array region of the substrate, and providinga second electrical node associated with said other region of thesubstrate; forming a first capacitor electrode in electrical connectionwith the first electrical node; in a common deposition step, forming aconductive material over the first capacitor electrode and in electricalconnection with the second electrical node; and forming a capacitordielectric layer and a second capacitor electrode ever the firstcapacitor electrode to form a capacitor construction comprising thecapacitor dielectric layer and the first and second capacitorelectrodes, one of the first and second capacitor electrodes comprisingthe conductive material.
 7. The method of claim 6 comprising: forming anelectrically conductive layer over the first capacitor electrode andover the second electrical node prior to the common deDesition step;xetching an opening through the wlectrically conductive layer to thesecond electrical node; and wherein the common deDosition steD forms theconductive matenal within the opening.
 8. The method of claim 7 whereinthe electrically conductive layer comprises at least one of TiN and WN.9. The method of claim 7 wherein the electrically conductive layercomprises TiN.
 10. The method of claim 7 further comprising forming thecapacitor dielectric layer over the first capacitor electrode beforeforming the electrically conductive layer.
 11. The method of claim 6wherein the semiconductive material comprises monocrystalline siliconand the electrical nodes comprise electrically conductive diffusionregions formed within the semiconductive material.
 12. The method ofclaim 6 wherein the forming the conductive material comprises forming ametal-comprising layer.
 13. The method of claim 6 wherein the formingthe conductive material comprises forming at least two layers.
 14. Themethod of claim 6 wherein the forming the conductive material comprisesforming at least three layers.
 15. The method of claim 6, wherein theforming the conductive material comprises: forming a layer comprisingTiN; and forming a second layer over the layer comprising TiN, thesecond layer not comprising TiN.